The proposed research involves studies of social and pheromonal factors influencing puberty in mammals. These studies have potential significance and application to three important biological problems related to humans: (1) Generation time is a critical parameter affecting population regulation. Factors which influence generation time are thus critical for an understanding of population regulation. (2) Menarche in human females occurs at earlier ages than a century ago. Studies of social factors affecting puberty and underlying physiological processes may help to explain this shift in menarche. (3) Discovery of pheromones which affect social behavior in mammals, including primates, make it increasingly necessary to gain a thorough understanding of pheromone production and effects on behavior and physiology. Investigations outlined in this proposal will use house mice as subjects and first vaginal estrus as a dependent variable to measure puberty. The long range goal is to obtain a relatively complete picture of pheromones produced by male and female mice which affect female maturation and factors which affect production of these pheromones. Four major lines of experimentation are planned; (1) studies of the role of genetic inheritance affecting puberty by artificial selection for early and late sexual maturation, (2) investigations of ovariectomy and adrenalectomy affecting production of a maturation-delaying pheromone by female mice, (3) experiments to test effects of prior sexual experience, social status and hormonal condition on male acceleration of female puberty, and (4) studies to explore possibilities that females at different stages of the reproductive cycle, including pregnancy and lactation, produce pheromones which affect puberty. These studies will lead to multi-factor experiments testing several social and pheromonal factors stimultaneously.